From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755985Ab2LHMMN (ORCPT ); Sat, 8 Dec 2012 07:12:13 -0500 Received: from 173-166-109-252-newengland.hfc.comcastbusiness.net ([173.166.109.252]:37076 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752614Ab2LHMML (ORCPT ); Sat, 8 Dec 2012 07:12:11 -0500 Date: Sat, 8 Dec 2012 07:12:04 -0500 From: Christoph Hellwig To: Dave Chinner Cc: Alun , Alexander Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: PATCH reduce impact of FIFREEZE on userland processes Message-ID: <20121208121204.GA18467@infradead.org> References: <20121205211707.7ca3b94b@aspire.ty-penguin.org.uk> <20121207004255.GC27172@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121207004255.GC27172@dastard> User-Agent: Mutt/1.5.21 (2010-09-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 07, 2012 at 11:42:55AM +1100, Dave Chinner wrote: > The problem wth doing this is that the sync can delay the freeze > process by quite some time under the exact conditions you describe. > If you want freeze to take effect immediately (i.e instantly stop > new modifications), then adding a sync will break this semantic. > THere are existing users of freeze that require this behaviour... But that's only because he uses the big hammer sync_filesystem() which actually waits for I/O completion. I agree that this is a bad idea, but if we'd just do a writeback_inodes_sb() call in this place that starts asynchronous writeout I think everyone would benefit.